A pump device, and a fuel supply device for an internal combustion engine, in particular of a motor vehicle, already emerge, so as to be known, for example from US 2012/0312278 A1. The fuel supply device serves for supplying fuel, in particular liquid fuel, to the internal combustion engine. The fuel supply device comprises a first injection device for effecting a direct injection of fuel. This means that the internal combustion engine has at least one combustion chamber into which the fuel is directly injected by means of the first injection device.
The fuel supply device furthermore comprises a second injection device, which is provided in addition to the first injection device, for effecting an induction pipe injection of fuel. During the course of the intake pipe injection of fuel, which is also referred to as intake pipe injection, the fuel is introduced, in particular injected, into the internal combustion engine at a location arranged upstream of the combustion chamber. The location is arranged for example in an intake pipe, through which air may flow, of the internal combustion engine, and upstream of an inlet valve of the internal combustion engine.
The fuel supply device furthermore comprises the abovementioned high-pressure fuel pump, by means of which the fuel is supplied to the first injection device. This means that the fuel is conveyed to the first injection device by means of the high-pressure fuel pump. The fuel supply device furthermore comprises a low-pressure fuel pump for conveying the fuel to the high-pressure fuel pump. By means of the low-pressure fuel pump, the fuel is conveyed for example at a first pressure. In other words, by means of the low-pressure fuel pump, a first pressure of the fuel that is conveyed by means of the low-pressure fuel pump is effected.
By means of the high-pressure fuel pump, the fuel is conveyed for example at a second pressure that is higher than the first pressure. In other words, by means of the high-pressure fuel pump, a second pressure of the fuel that is higher than the first pressure is effected. In this way, it is for example possible for the first injection device to be supplied with the second pressure that is higher than the first pressure, where the second injection device is supplied with the first pressure.
The high-pressure fuel pump has at least one low-pressure inlet via which fuel is fed to the high-pressure fuel pump from the low-pressure fuel pump. This means that at least a part of the fuel conveyed by means of the low-pressure fuel pump is fed via the low-pressure inlet to the high-pressure fuel pump.
The high-pressure fuel pump furthermore has at least one low-pressure outlet for conducting fuel conveyed by means of the low-pressure fuel pump and fed via the low-pressure inlet to the high-pressure fuel pump out of the high-pressure fuel pump. This means that at least a part of the fuel that flows via the low-pressure inlet into the high-pressure fuel pump may flow out of or away from the high-pressure fuel pump via the low-pressure outlet, where, for example, the fuel flowing through the low-pressure outlet is at the first pressure effected by means of the low-pressure fuel pump. Thus, for example, the fuel flowing through the low-pressure outlet is not compressed by means of the high-pressure fuel pump.
Furthermore, the device comprises at least one low-pressure port for conducting fuel conveyed by means of the low-pressure fuel pump to the second injection device which is provided in addition to the first injection device. This means that the fuel that is for example at the first pressure is conducted by means of the low-pressure port to the second injection device, such that the second injection device is supplied via the low-pressure port with fuel that is in particular at the first pressure.
Furthermore, WO 2012/004084 A1 discloses a fuel system for an internal combustion engine, having a low-pressure conveying device which conveys at least indirectly to at least one low-pressure injection device. The fuel system furthermore comprises a high-pressure conveying device for the fuel, which high-pressure conveying device has a drive region and a conveying region and conveys at least indirectly to at least one high-pressure injection device. It is provided here that the fuel is conveyed from the low-pressure conveying device firstly into the drive region of the high-pressure conveying device and from there onward to the low-pressure injection device and/or to the conveying region of the high-pressure conveying device.